Molecular subtyping and virulence gene analysis of Listeria monocytogenes isolates from food |
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Authors: | Jinling Shen Lydia Rump Yifan Zhang Yi Chen Xin Wang Jianghong Meng |
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Affiliation: | 1. College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi Province 712100, China;2. Department of Nutrition and Food Science, University of Maryland, College Park, MD 20742, USA;3. Department of Nutrition and Food Science, Wayne State University, Detroit, MI 48202, USA;4. Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, College Park, MD 20740, USA |
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Abstract: | A total of 67 Listeria monocytogenes isolates from 698 raw meat samples were characterized for molecular serogroup identification and antimicrobial susceptibility. Approximately one third (32.8%) of the isolates belonged to molecular serogroup 1/2a, 3a, followed by 1/2c, 3c (26.9%), 1/2b, 3b, 7 (22.4%), 4b, 4d, 4e (16.4%) and 4a, 4c (1.5%). Most of the L. monocytogenes isolates were susceptible to 14 antimicrobials tested but several were resistant to tetracycline, ciprofloxacin and nitrofurantoin. An additional 30 L. monocytogenes isolates from chicken and produce in our collection were also included to determine the presence of significant virulence markers. All 97 isolates carried inlC and inlJ except for a lineage III isolate 110-1. Most Listeriolysin S (LLS)-carrying isolates (11/12) belonged to lineage I, whereas the remaining one isolate belonged to lineage III. Five 4b, 4d, 4e isolates including two from turkey and three from produce belonged to Epidemic Clone I (ECI). Four molecular serogroup associated mutation types that lead to premature stop codons (PMSCs) in inlA were identified. PFGE and inlA sequence analysis results were concordant, and different virulence potential within 1/2a, 3a and 4b, 4d, 4e isolates were observed. The study revealed that a subset of isolates from meat and produce belonged to ECI, harbored inlC, inlJ and LLS, and produced full length InlA, suggesting that they be capable of causing human illness. |
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Keywords: | Listeria monocytogenes inlA Epidemic clone Listeriolysin S |
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